1. Field of the Invention
The present invention relates to a display control device for a dot-matrix type liquid-crystal display device.
2. Description of the Related Art
A dot-matrix type liquid-crystal display device comprises a liquid-crystal panel, a common electrode driver for applying driving signals (scan pulses) to common electrodes, a data electrode driver for applying data signals to data electrodes, and a controller for controlling these drivers. Such a display device is driven by a so-called voltage averaging method. In this method, assuming that the dot matrix employed in the display device consists of m rows and n columns, a driving signal i.sub.v is applied to the ith row common electrode, a data signal j.sub.v is applied to the jth column data electrode, and a voltage corresponding to the difference i.sub.v -j.sub.v between these signals is applied to a dot located on an intersection point of the ith row and the jth column.
If the signals i.sub.v and j.sub.v have ideal rectangular waveforms, no disadvantage occurs on the display. However, actual waveforms are subject to a rounding or ringing phenomenon, so that ghost or luminance unevenness occurs on the display as described in detail later.